Seppo Renfors wrote:
Tom McDonald wrote:
Seppo Renfors wrote:
Gary Coffman wrote:
On Tue, 29 Jun 2004 05:48:01 GMT, Seppo Renfors
wrote:
Gary Coffman wrote:
[..]
Again, porosity is the problem, and that should
show up on radiographs, as it does for R666 (which
certainly shows evidence of being melted in
atmosphere, though not necessarily evidence of
being cast), but none of the other artifacts
presented show that sort of porosity.
See: http://www.iwaynet.net/~wdc/copper.htm
The 4th and 5th pictures down.
Those pictures do not show any evidence of the
characteristic porosity copper casting would produce.
They disagree with you as it states "The casting bubble
can clearly been seen...."
Gary showed that the porosity typical of pure cast copper
is not present in that artifact. He even explained in just
below.
Please point out the "porosity" in this sample:
Two copper pigs: http://people.uncw.edu/simmonss/P6030052.JPG
The casting is obvious in this:
http://people.uncw.edu/simmonss/LA_1240-1.4.jpg
Both pictures show melted copper - pre Colombian melted
copper! It leaves Gary's statements hanging in the air.
Seppo,
First, the porosity would be most likely visible on
radiographs, or in a section through the bubbles. You haven't
given me the information necessary to determine this for these
copper pieces.
Second, no one argues that no copper was ever melted in
pre-Columbian North America. The question, especially for the
upper Great Lakes area, is whether this was done by humans; and
if so, whether it was done on purpose to make tools or ornaments.
Third, the artifacts shown are from Lamanai, Belize, and
date from after about 1200 AD. They have el zippo to do with
copper work in the Upper Great Lakes area in the Archaic. Is
that why you posted links to the photos, but not to the web page
they're on? That page specifies all this:
"Copper and bronze (copper-tin and copper-arsenic) began to
arrive at Lamanai during the 13th century AD. Provenience
studies conducted by Dr. Dorothy Hosler at the Massachusetts
Institute of Technology revealed that the copper used to produce
many of these items was obtained from West Mexican ore fields."
http://people.uncw.edu/simmonss/lamanai.htm
However if one considers that "bubbling" has been claimed to
be caused by "overheating" in a annealing process - then it
is saying "melted" at the same time, as it cannot bubble
UNLESS a portion of it is melted. Also "welding" requires the
melting of the metal - or so goddamned close to it that the
friction heat generated by a blow on it does melt the metal.
This is grasping at straws, Seppo.
Those are two logical examples of melting occurring - the
knowledge of melting copper existed. It beggars belief that
scraps and off cuts were NOT melted when the process must
have been known to them. That people suggest they would
rather go and do hard manual labour another day to find a
piece "just right" for the job, when it is right there, right
now, right before them. All they have to do is melt it into
one lump.
Woulda coulda shoulda. As Inger what value to place on
'what-if's'.
The implied suggestion they would rather do the hard labour,
and not proceed with the easier option available immediately
to them, isn't consistent with known human behaviour.
The implied suggestion is that the Indians wisely used the
techniques that produced the best tools and ornaments for them.
As Gary has pointed out, often, and you seem not to have
grasped, casting pure copper is very inferior to forging pure
copper in terms of the quality of the finished product.
Choosing to use a process that produces a lower quality result
over a well-known process that produces a higher quality result
is not consistent with known human behavior.
Tom McDonald
[..]